AN IMPROVED METHOD FOR PREPARATION OF SUBSTITUTED TETRAHYDROISOQUINOLINES

摘要

An improved method for the preparation and isolation of optically pure (3S) or (3R)-1, 2, 3, 4-tetrahydroisoquinoline-3-carboxylic acid comprises reacting formaldehyde with either D- or L-phenylalanine and hydrobromic acid to prepare the pure hydrobromide salts. The mixture is then cooled to precipitate the optically pure isomer which is filtered and then neutralized with a base to form the free acid and dried.